Interrupt set register
| RX_TRIGGER | Write with ‘1’ to set corresponding bit in interrupt request register. |
| RX_NOT_EMPTY | Write with ‘1’ to set corresponding bit in interrupt request register. |
| RX_OVERFLOW | Write with ‘1’ to set corresponding bit in interrupt request register. |
| RX_UNDERFLOW | Write with ‘1’ to set corresponding bit in interrupt request register. |